Why are my tomato plants with curled leaves and how can I fix this issue?

Curled leaves on tomato plants can be caused by various factors such as pests, diseases, or environmental stress. To fix this issue, you can start by checking for signs of pests like aphids or mites, treating any diseases with appropriate fungicides, and ensuring the plants are receiving adequate water and sunlight. Additionally, maintaining proper soil pH and providing sufficient nutrients can help promote healthy leaf growth.